From the deep reds of a cabernet to the light pinks of a ros/e/ , wine color is due to a group of compounds known as anthocyanins. Naturally present in wine grapes, anthocyanins are found primarily in the grape skin, and to a lesser extent, in the pulp of the grape. The depth or intensity of the color of a wine is based on the amount of color in the pulp plus the time that the skins are in contact with the pulp after being crushed into a grape must. For example, the pulp of the Pinot Noir grape has a pink color, but when the skins are present during fermentation, a deep red color is imparted.
Normally, changing the color of a wine is of little interest to a vintner. However, today the popularity of white wines exceeds the capacity of the vineyards to grow traditional white wine grapes. Thus, the ability to remove color from grapes and enable "red wine grapes" to produce white wines is significant.